Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 78Get this manual
2Start engine and allow to warm upIncrease engine RPM from idle to 2000Normal voltage output should be 13.5 -15.1 voltsIf voltage reading is greater than normal, replace voltage regulator 5With TERMINAL grounded, voltage should rise to within the normal range (13.5 -15.1)If voltage rises, replace the regulator
3If voltage reading is less than normal, fabricate a
tool from piece of stiff wire to the following specifications:
6If the voltage DOES NOT rise to within the normal range with TERMINAL grounded, perform
"CURRENT OUTPUT" testCURRENT OUTPUT
0.060 in(1.52mm)
1With engine shut off, install ammeter (capable of reading 60+ amperes) in series between TERMINAL on alternator and POSITIVE (+) terminal of battery